It's that time of the year again. Pull out the butter and protractors because Pi Day is before us! Every March 14 we honor the math constant pi (3.14159..) with many slices of its delicious homophone pie. This year we're teaming up with the fun folks at Instructables to host the 2011 Pi Day Contest, which will run until March 20. Find out all the contest details here! First place pie will win an iPad engraved with the first 314 digits of pi—how sweet is that?!